The Tor Browser: layout/style/nsTransitionManager.cpp@b8a032363ba2 (annotated)

layout/style/nsTransitionManager.cpp@b8a032363ba2 (annotated)

layout/style/nsTransitionManager.cpp

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* vim: set shiftwidth=2 tabstop=8 autoindent cindent expandtab: */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 /* Code to start and animate CSS transitions. */
 #include "nsTransitionManager.h"
 #include "nsAnimationManager.h"
 #include "nsIContent.h"
 #include "nsStyleContext.h"
 #include "nsCSSProps.h"
 #include "mozilla/MemoryReporting.h"
 #include "mozilla/TimeStamp.h"
 #include "nsRefreshDriver.h"
 #include "nsRuleProcessorData.h"
 #include "nsRuleWalker.h"
 #include "nsCSSPropertySet.h"
 #include "nsStyleAnimation.h"
 #include "mozilla/EventDispatcher.h"
 #include "mozilla/ContentEvents.h"
 #include "mozilla/dom/Element.h"
 #include "nsIFrame.h"
 #include "Layers.h"
 #include "FrameLayerBuilder.h"
 #include "nsDisplayList.h"
 #include "nsStyleChangeList.h"
 #include "nsStyleSet.h"
 #include "RestyleManager.h"
 #include "ActiveLayerTracker.h"
 using mozilla::TimeStamp;
 using mozilla::TimeDuration;
 using namespace mozilla;
 using namespace mozilla::layers;
 using namespace mozilla::css;
 ElementTransitions::ElementTransitions(mozilla::dom::Element *aElement,
                                        nsIAtom *aElementProperty,
                                        nsTransitionManager *aTransitionManager,
                                        TimeStamp aNow)
   : CommonElementAnimationData(aElement, aElementProperty,
                                aTransitionManager, aNow)
 {
 }
 double
 ElementPropertyTransition::ValuePortionFor(TimeStamp aRefreshTime) const
 {
   // Set |timePortion| to the portion of the way we are through the time
   // input to the transition's timing function (always within the range
   // 0-1).
   double duration = mIterationDuration.ToSeconds();
   NS_ABORT_IF_FALSE(duration >= 0.0, "negative duration forbidden");
   double timePortion;
   if (IsRemovedSentinel()) {
     // The transition is being removed, but we still want an update so that any
     // new transitions start in the right place.
     timePortion = 1.0;
   } else if (duration == 0.0) {
     // When duration is zero, we can still have a transition when delay
     // is nonzero.
     if (aRefreshTime >= mStartTime + mDelay) {
       timePortion = 1.0;
     } else {
       timePortion = 0.0;
     }
   } else {
     timePortion = (aRefreshTime - (mStartTime + mDelay)).ToSeconds() / duration;
     if (timePortion < 0.0)
       timePortion = 0.0; // use start value during transition-delay
     if (timePortion > 1.0)
       timePortion = 1.0; // we might be behind on flushing
   }
   MOZ_ASSERT(mProperties.Length() == 1,
              "Should have one animation property for a transition");
   MOZ_ASSERT(mProperties[0].mSegments.Length() == 1,
              "Animation property should have one segment for a transition");
   return mProperties[0].mSegments[0].mTimingFunction.GetValue(timePortion);
 }
 static void
 ElementTransitionsPropertyDtor(void           *aObject,
                                nsIAtom        *aPropertyName,
                                void           *aPropertyValue,
                                void           *aData)
 {
   ElementTransitions *et = static_cast<ElementTransitions*>(aPropertyValue);
 #ifdef DEBUG
   NS_ABORT_IF_FALSE(!et->mCalledPropertyDtor, "can't call dtor twice");
   et->mCalledPropertyDtor = true;
 #endif
   delete et;
 }
 void
 ElementTransitions::EnsureStyleRuleFor(TimeStamp aRefreshTime)
 {
   if (!mStyleRule || mStyleRuleRefreshTime != aRefreshTime) {
     mStyleRule = new css::AnimValuesStyleRule();
     mStyleRuleRefreshTime = aRefreshTime;
     for (uint32_t i = 0, i_end = mPropertyTransitions.Length(); i < i_end; ++i)
     {
       ElementPropertyTransition &pt = mPropertyTransitions[i];
       if (pt.IsRemovedSentinel()) {
         continue;
       }
       MOZ_ASSERT(pt.mProperties.Length() == 1,
                  "Should have one animation property for a transition");
       const AnimationProperty &prop = pt.mProperties[0];
       nsStyleAnimation::Value *val = mStyleRule->AddEmptyValue(prop.mProperty);
       double valuePortion = pt.ValuePortionFor(aRefreshTime);
       MOZ_ASSERT(prop.mSegments.Length() == 1,
                  "Animation property should have one segment for a transition");
 #ifdef DEBUG
       bool ok =
 #endif
         nsStyleAnimation::Interpolate(prop.mProperty,
                                       prop.mSegments[0].mFromValue,
                                       prop.mSegments[0].mToValue,
                                       valuePortion, *val);
       NS_ABORT_IF_FALSE(ok, "could not interpolate values");
     }
   }
 }
 bool
 ElementTransitions::HasAnimationOfProperty(nsCSSProperty aProperty) const
 {
   for (uint32_t tranIdx = mPropertyTransitions.Length(); tranIdx-- != 0; ) {
     const ElementPropertyTransition& pt = mPropertyTransitions[tranIdx];
     if (pt.HasAnimationOfProperty(aProperty) && !pt.IsRemovedSentinel()) {
       return true;
     }
   }
   return false;
 }
 bool
 ElementTransitions::CanPerformOnCompositorThread(CanAnimateFlags aFlags) const
 {
   nsIFrame* frame = nsLayoutUtils::GetStyleFrame(mElement);
   if (!frame) {
     return false;
   }
   if (mElementProperty != nsGkAtoms::transitionsProperty) {
     if (nsLayoutUtils::IsAnimationLoggingEnabled()) {
       nsCString message;
       message.AppendLiteral("Gecko bug: Async transition of pseudoelements not supported.  See bug 771367");
       LogAsyncAnimationFailure(message, mElement);
     }
     return false;
   }
   TimeStamp now = frame->PresContext()->RefreshDriver()->MostRecentRefresh();
   for (uint32_t i = 0, i_end = mPropertyTransitions.Length(); i < i_end; ++i) {
     const ElementPropertyTransition& pt = mPropertyTransitions[i];
     MOZ_ASSERT(pt.mProperties.Length() == 1,
                "Should have one animation property for a transition");
     if (css::IsGeometricProperty(pt.mProperties[0].mProperty) &&
         pt.IsRunningAt(now)) {
       aFlags = CanAnimateFlags(aFlags | CanAnimate_HasGeometricProperty);
       break;
     }
   }
   bool hasOpacity = false;
   bool hasTransform = false;
   bool existsProperty = false;
   for (uint32_t i = 0, i_end = mPropertyTransitions.Length(); i < i_end; ++i) {
     const ElementPropertyTransition& pt = mPropertyTransitions[i];
     if (!pt.IsRunningAt(now)) {
       continue;
     }
     existsProperty = true;
     MOZ_ASSERT(pt.mProperties.Length() == 1,
                "Should have one animation property for a transition");
     const AnimationProperty& prop = pt.mProperties[0];
     if (!css::CommonElementAnimationData::CanAnimatePropertyOnCompositor(
           mElement, prop.mProperty, aFlags) ||
         css::CommonElementAnimationData::IsCompositorAnimationDisabledForFrame(frame)) {
       return false;
     }
     if (prop.mProperty == eCSSProperty_opacity) {
       hasOpacity = true;
     } else if (prop.mProperty == eCSSProperty_transform) {
       hasTransform = true;
     }
   }
   // No properties to animate
   if (!existsProperty) {
     return false;
   }
   // This transition can be done on the compositor.  Mark the frame as active, in
   // case we are able to throttle this transition.
   if (hasOpacity) {
     ActiveLayerTracker::NotifyAnimated(frame, eCSSProperty_opacity);
   }
   if (hasTransform) {
     ActiveLayerTracker::NotifyAnimated(frame, eCSSProperty_transform);
   }
   return true;
 }
 /*****************************************************************************
  * nsTransitionManager                                                       *
  *****************************************************************************/
 void
 nsTransitionManager::UpdateThrottledStylesForSubtree(nsIContent* aContent,
                                                      nsStyleContext* aParentStyle,
                                                      nsStyleChangeList& aChangeList)
 {
   dom::Element* element;
   if (aContent->IsElement()) {
     element = aContent->AsElement();
   } else {
     element = nullptr;
   }
   nsRefPtr<nsStyleContext> newStyle;
   ElementTransitions* et;
   if (element &&
       (et = GetElementTransitions(element,
                                   nsCSSPseudoElements::ePseudo_NotPseudoElement,
                                   false))) {
     // re-resolve our style
     newStyle = UpdateThrottledStyle(element, aParentStyle, aChangeList);
     // remove the current transition from the working set
     et->mFlushGeneration = mPresContext->RefreshDriver()->MostRecentRefresh();
   } else {
     newStyle = ReparentContent(aContent, aParentStyle);
   }
   // walk the children
   if (newStyle) {
     for (nsIContent *child = aContent->GetFirstChild(); child;
          child = child->GetNextSibling()) {
       UpdateThrottledStylesForSubtree(child, newStyle, aChangeList);
     }
   }
 }
 IMPL_UPDATE_ALL_THROTTLED_STYLES_INTERNAL(nsTransitionManager,
                                           GetElementTransitions)
 void
 nsTransitionManager::UpdateAllThrottledStyles()
 {
   if (PR_CLIST_IS_EMPTY(&mElementData)) {
     // no throttled transitions, leave early
     mPresContext->TickLastUpdateThrottledTransitionStyle();
     return;
   }
   if (mPresContext->ThrottledTransitionStyleIsUpToDate()) {
     // throttled transitions are up to date, leave early
     return;
   }
   mPresContext->TickLastUpdateThrottledTransitionStyle();
   UpdateAllThrottledStylesInternal();
 }
 void
 nsTransitionManager::ElementDataRemoved()
 {
   // If we have no transitions or animations left, remove ourselves from
   // the refresh driver.
   if (PR_CLIST_IS_EMPTY(&mElementData)) {
     mPresContext->RefreshDriver()->RemoveRefreshObserver(this, Flush_Style);
   }
 }
 void
 nsTransitionManager::AddElementData(CommonElementAnimationData* aData)
 {
   if (PR_CLIST_IS_EMPTY(&mElementData)) {
     // We need to observe the refresh driver.
     nsRefreshDriver *rd = mPresContext->RefreshDriver();
     rd->AddRefreshObserver(this, Flush_Style);
   }
   PR_INSERT_BEFORE(aData, &mElementData);
 }
 already_AddRefed<nsIStyleRule>
 nsTransitionManager::StyleContextChanged(dom::Element *aElement,
                                          nsStyleContext *aOldStyleContext,
                                          nsStyleContext *aNewStyleContext)
 {
   NS_PRECONDITION(aOldStyleContext->GetPseudo() ==
                       aNewStyleContext->GetPseudo(),
                   "pseudo type mismatch");
   // If we were called from ReparentStyleContext, this assertion would
   // actually fire.  If we need to be called from there, we can probably
   // just remove it; the condition probably isn't critical, although
   // it's worth thinking about some more.
   NS_PRECONDITION(aOldStyleContext->HasPseudoElementData() ==
                       aNewStyleContext->HasPseudoElementData(),
                   "pseudo type mismatch");
   if (!mPresContext->IsDynamic()) {
     // For print or print preview, ignore transitions.
     return nullptr;
   }
   // NOTE: Things in this function (and ConsiderStartingTransition)
   // should never call PeekStyleData because we don't preserve gotten
   // structs across reframes.
   // Return sooner (before the startedAny check below) for the most
   // common case: no transitions specified or running.
   const nsStyleDisplay *disp = aNewStyleContext->StyleDisplay();
   nsCSSPseudoElements::Type pseudoType = aNewStyleContext->GetPseudoType();
   if (pseudoType != nsCSSPseudoElements::ePseudo_NotPseudoElement) {
     if (pseudoType != nsCSSPseudoElements::ePseudo_before &&
         pseudoType != nsCSSPseudoElements::ePseudo_after) {
       return nullptr;
     }
     NS_ASSERTION((pseudoType == nsCSSPseudoElements::ePseudo_before &&
                   aElement->Tag() == nsGkAtoms::mozgeneratedcontentbefore) ||
                  (pseudoType == nsCSSPseudoElements::ePseudo_after &&
                   aElement->Tag() == nsGkAtoms::mozgeneratedcontentafter),
                  "Unexpected aElement coming through");
     // Else the element we want to use from now on is the element the
     // :before or :after is attached to.
     aElement = aElement->GetParent()->AsElement();
   }
   ElementTransitions *et =
       GetElementTransitions(aElement, pseudoType, false);
   if (!et &&
       disp->mTransitionPropertyCount == 1 &&
       disp->mTransitions[0].GetDelay() == 0.0f &&
       disp->mTransitions[0].GetDuration() == 0.0f) {
     return nullptr;
   }
   if (aNewStyleContext->PresContext()->IsProcessingAnimationStyleChange()) {
     return nullptr;
   }
   if (aNewStyleContext->GetParent() &&
       aNewStyleContext->GetParent()->HasPseudoElementData()) {
     // Ignore transitions on things that inherit properties from
     // pseudo-elements.
     // FIXME (Bug 522599): Add tests for this.
     return nullptr;
   }
   NS_WARN_IF_FALSE(!nsLayoutUtils::AreAsyncAnimationsEnabled() ||
                      mPresContext->ThrottledTransitionStyleIsUpToDate(),
                    "throttled animations not up to date");
   // Per http://lists.w3.org/Archives/Public/www-style/2009Aug/0109.html
   // I'll consider only the transitions from the number of items in
   // 'transition-property' on down, and later ones will override earlier
   // ones (tracked using |whichStarted|).
   bool startedAny = false;
   nsCSSPropertySet whichStarted;
   for (uint32_t i = disp->mTransitionPropertyCount; i-- != 0; ) {
     const nsTransition& t = disp->mTransitions[i];
     // Check delay and duration first, since they default to zero, and
     // when they're both zero, we can ignore the transition.
     if (t.GetDelay() != 0.0f || t.GetDuration() != 0.0f) {
       // We might have something to transition.  See if any of the
       // properties in question changed and are animatable.
       // FIXME: Would be good to find a way to share code between this
       // interpretation of transition-property and the one below.
       nsCSSProperty property = t.GetProperty();
       if (property == eCSSPropertyExtra_no_properties ||
           property == eCSSPropertyExtra_variable ||
           property == eCSSProperty_UNKNOWN) {
         // Nothing to do, but need to exclude this from cases below.
       } else if (property == eCSSPropertyExtra_all_properties) {
         for (nsCSSProperty p = nsCSSProperty(0);
              p < eCSSProperty_COUNT_no_shorthands;
              p = nsCSSProperty(p + 1)) {
           ConsiderStartingTransition(p, t, aElement, et,
                                      aOldStyleContext, aNewStyleContext,
                                      &startedAny, &whichStarted);
         }
       } else if (nsCSSProps::IsShorthand(property)) {
         CSSPROPS_FOR_SHORTHAND_SUBPROPERTIES(subprop, property) {
           ConsiderStartingTransition(*subprop, t, aElement, et,
                                      aOldStyleContext, aNewStyleContext,
                                      &startedAny, &whichStarted);
         }
       } else {
         ConsiderStartingTransition(property, t, aElement, et,
                                    aOldStyleContext, aNewStyleContext,
                                    &startedAny, &whichStarted);
       }
     }
   }
   // Stop any transitions for properties that are no longer in
   // 'transition-property'.
   // Also stop any transitions for properties that just changed (and are
   // still in the set of properties to transition), but we didn't just
   // start the transition because delay and duration are both zero.
   if (et) {
     bool checkProperties =
       disp->mTransitions[0].GetProperty() != eCSSPropertyExtra_all_properties;
     nsCSSPropertySet allTransitionProperties;
     if (checkProperties) {
       for (uint32_t i = disp->mTransitionPropertyCount; i-- != 0; ) {
         const nsTransition& t = disp->mTransitions[i];
         // FIXME: Would be good to find a way to share code between this
         // interpretation of transition-property and the one above.
         nsCSSProperty property = t.GetProperty();
         if (property == eCSSPropertyExtra_no_properties ||
             property == eCSSPropertyExtra_variable ||
             property == eCSSProperty_UNKNOWN) {
           // Nothing to do, but need to exclude this from cases below.
         } else if (property == eCSSPropertyExtra_all_properties) {
           for (nsCSSProperty p = nsCSSProperty(0);
                p < eCSSProperty_COUNT_no_shorthands;
                p = nsCSSProperty(p + 1)) {
             allTransitionProperties.AddProperty(p);
           }
         } else if (nsCSSProps::IsShorthand(property)) {
           CSSPROPS_FOR_SHORTHAND_SUBPROPERTIES(subprop, property) {
             allTransitionProperties.AddProperty(*subprop);
           }
         } else {
           allTransitionProperties.AddProperty(property);
         }
       }
     }
     nsTArray<ElementPropertyTransition> &pts = et->mPropertyTransitions;
     uint32_t i = pts.Length();
     NS_ABORT_IF_FALSE(i != 0, "empty transitions list?");
     nsStyleAnimation::Value currentValue;
     do {
       --i;
       ElementPropertyTransition &pt = pts[i];
       MOZ_ASSERT(pt.mProperties.Length() == 1,
                  "Should have one animation property for a transition");
       MOZ_ASSERT(pt.mProperties[0].mSegments.Length() == 1,
                  "Animation property should have one segment for a transition");
       const AnimationProperty& prop = pt.mProperties[0];
       const AnimationPropertySegment& segment = prop.mSegments[0];
           // properties no longer in 'transition-property'
       if ((checkProperties &&
            !allTransitionProperties.HasProperty(prop.mProperty)) ||
           // properties whose computed values changed but delay and
           // duration are both zero
           !ExtractComputedValueForTransition(prop.mProperty, aNewStyleContext,
                                              currentValue) ||
           currentValue != segment.mToValue) {
         // stop the transition
         pts.RemoveElementAt(i);
         et->UpdateAnimationGeneration(mPresContext);
       }
     } while (i != 0);
     if (pts.IsEmpty()) {
       et->Destroy();
       et = nullptr;
     }
   }
   if (!startedAny) {
     return nullptr;
   }
   NS_ABORT_IF_FALSE(et, "must have element transitions if we started "
                         "any transitions");
   // In the CSS working group discussion (2009 Jul 15 telecon,
   // http://www.w3.org/mid/4A5E1470.4030904@inkedblade.net ) of
   // http://lists.w3.org/Archives/Public/www-style/2009Jun/0121.html ,
   // the working group decided that a transition property on an
   // element should not cause any transitions if the property change
   // is itself inheriting a value that is transitioning on an
   // ancestor.  So, to get the correct behavior, we continue the
   // restyle that caused this transition using a "covering" rule that
   // covers up any changes on which we started transitions, so that
   // descendants don't start their own transitions.  (In the case of
   // negative transition delay, this covering rule produces different
   // results than applying the transition rule immediately would).
   // Our caller is responsible for restyling again using this covering
   // rule.
   nsRefPtr<css::AnimValuesStyleRule> coverRule = new css::AnimValuesStyleRule;
   nsTArray<ElementPropertyTransition> &pts = et->mPropertyTransitions;
   for (uint32_t i = 0, i_end = pts.Length(); i < i_end; ++i) {
     ElementPropertyTransition &pt = pts[i];
     MOZ_ASSERT(pt.mProperties.Length() == 1,
                "Should have one animation property for a transition");
     MOZ_ASSERT(pt.mProperties[0].mSegments.Length() == 1,
                "Animation property should have one segment for a transition");
     AnimationProperty& prop = pt.mProperties[0];
     AnimationPropertySegment& segment = prop.mSegments[0];
     if (whichStarted.HasProperty(prop.mProperty)) {
       coverRule->AddValue(prop.mProperty, segment.mFromValue);
     }
   }
   et->mStyleRule = nullptr;
   return coverRule.forget();
 }
 void
 nsTransitionManager::ConsiderStartingTransition(nsCSSProperty aProperty,
                                                 const nsTransition& aTransition,
                                                 dom::Element* aElement,
                                                 ElementTransitions*& aElementTransitions,
                                                 nsStyleContext* aOldStyleContext,
                                                 nsStyleContext* aNewStyleContext,
                                                 bool* aStartedAny,
                                                 nsCSSPropertySet* aWhichStarted)
 {
   // IsShorthand itself will assert if aProperty is not a property.
   NS_ABORT_IF_FALSE(!nsCSSProps::IsShorthand(aProperty),
                     "property out of range");
   NS_ASSERTION(!aElementTransitions ||
                aElementTransitions->mElement == aElement, "Element mismatch");
   if (aWhichStarted->HasProperty(aProperty)) {
     // A later item in transition-property already started a
     // transition for this property, so we ignore this one.
     // See comment above and
     // http://lists.w3.org/Archives/Public/www-style/2009Aug/0109.html .
     return;
   }
   if (nsCSSProps::kAnimTypeTable[aProperty] == eStyleAnimType_None) {
     return;
   }
   ElementPropertyTransition pt;
   nsStyleAnimation::Value startValue, endValue, dummyValue;
   bool haveValues =
     ExtractComputedValueForTransition(aProperty, aOldStyleContext,
                                       startValue) &&
     ExtractComputedValueForTransition(aProperty, aNewStyleContext,
                                       endValue);
   bool haveChange = startValue != endValue;
   bool shouldAnimate =
     haveValues &&
     haveChange &&
     // Check that we can interpolate between these values
     // (If this is ever a performance problem, we could add a
     // CanInterpolate method, but it seems fine for now.)
     nsStyleAnimation::Interpolate(aProperty, startValue, endValue,
 .5, dummyValue);
   bool haveCurrentTransition = false;
   uint32_t currentIndex = nsTArray<ElementPropertyTransition>::NoIndex;
   const ElementPropertyTransition *oldPT = nullptr;
   if (aElementTransitions) {
     nsTArray<ElementPropertyTransition> &pts =
       aElementTransitions->mPropertyTransitions;
     for (uint32_t i = 0, i_end = pts.Length(); i < i_end; ++i) {
       MOZ_ASSERT(pts[i].mProperties.Length() == 1,
                  "Should have one animation property for a transition");
       if (pts[i].mProperties[0].mProperty == aProperty) {
         haveCurrentTransition = true;
         currentIndex = i;
         oldPT = &aElementTransitions->mPropertyTransitions[currentIndex];
         break;
       }
     }
   }
   // If we got a style change that changed the value to the endpoint
   // of the currently running transition, we don't want to interrupt
   // its timing function.
   // This needs to be before the !shouldAnimate && haveCurrentTransition
   // case below because we might be close enough to the end of the
   // transition that the current value rounds to the final value.  In
   // this case, we'll end up with shouldAnimate as false (because
   // there's no value change), but we need to return early here rather
   // than cancel the running transition because shouldAnimate is false!
   MOZ_ASSERT(!oldPT || oldPT->mProperties[0].mSegments.Length() == 1,
              "Should have one animation property segment for a transition");
   if (haveCurrentTransition && haveValues &&
       oldPT->mProperties[0].mSegments[0].mToValue == endValue) {
     // WalkTransitionRule already called RestyleForAnimation.
     return;
   }
   nsPresContext *presContext = aNewStyleContext->PresContext();
   if (!shouldAnimate) {
     if (haveCurrentTransition) {
       // We're in the middle of a transition, and just got a non-transition
       // style change to something that we can't animate.  This might happen
       // because we got a non-transition style change changing to the current
       // in-progress value (which is particularly easy to cause when we're
       // currently in the 'transition-delay').  It also might happen because we
       // just got a style change to a value that can't be interpolated.
       nsTArray<ElementPropertyTransition> &pts =
         aElementTransitions->mPropertyTransitions;
       pts.RemoveElementAt(currentIndex);
       aElementTransitions->UpdateAnimationGeneration(mPresContext);
       if (pts.IsEmpty()) {
         aElementTransitions->Destroy();
         // |aElementTransitions| is now a dangling pointer!
         aElementTransitions = nullptr;
       }
       // WalkTransitionRule already called RestyleForAnimation.
     }
     return;
   }
   TimeStamp mostRecentRefresh =
     presContext->RefreshDriver()->MostRecentRefresh();
   const nsTimingFunction &tf = aTransition.GetTimingFunction();
   float delay = aTransition.GetDelay();
   float duration = aTransition.GetDuration();
   if (duration < 0.0) {
     // The spec says a negative duration is treated as zero.
     duration = 0.0;
   }
   pt.mStartForReversingTest = startValue;
   pt.mReversePortion = 1.0;
   // If the new transition reverses an existing one, we'll need to
   // handle the timing differently.
   if (haveCurrentTransition &&
       !oldPT->IsRemovedSentinel() &&
       oldPT->mStartForReversingTest == endValue) {
     // Compute the appropriate negative transition-delay such that right
     // now we'd end up at the current position.
     double valuePortion =
       oldPT->ValuePortionFor(mostRecentRefresh) * oldPT->mReversePortion +
       (1.0 - oldPT->mReversePortion);
     // A timing function with negative y1 (or y2!) might make
     // valuePortion negative.  In this case, we still want to apply our
     // reversing logic based on relative distances, not make duration
     // negative.
     if (valuePortion < 0.0) {
       valuePortion = -valuePortion;
     }
     // A timing function with y2 (or y1!) greater than one might
     // advance past its terminal value.  It's probably a good idea to
     // clamp valuePortion to be at most one to preserve the invariant
     // that a transition will complete within at most its specified
     // time.
     if (valuePortion > 1.0) {
       valuePortion = 1.0;
     }
     // Negative delays are essentially part of the transition
     // function, so reduce them along with the duration, but don't
     // reduce positive delays.
     if (delay < 0.0f) {
       delay *= valuePortion;
     }
     duration *= valuePortion;
     pt.mStartForReversingTest = oldPT->mProperties[0].mSegments[0].mToValue;
     pt.mReversePortion = valuePortion;
   }
   AnimationProperty& prop = *pt.mProperties.AppendElement();
   prop.mProperty = aProperty;
   AnimationPropertySegment& segment = *prop.mSegments.AppendElement();
   segment.mFromValue = startValue;
   segment.mToValue = endValue;
   segment.mFromKey = 0;
   segment.mToKey = 1;
   segment.mTimingFunction.Init(tf);
   pt.mStartTime = mostRecentRefresh;
   pt.mDelay = TimeDuration::FromMilliseconds(delay);
   pt.mIterationDuration = TimeDuration::FromMilliseconds(duration);
   pt.mIterationCount = 1;
   pt.mDirection = NS_STYLE_ANIMATION_DIRECTION_NORMAL;
   pt.mFillMode = NS_STYLE_ANIMATION_FILL_MODE_BACKWARDS;
   pt.mPlayState = NS_STYLE_ANIMATION_PLAY_STATE_RUNNING;
   pt.mPauseStart = TimeStamp();
   if (!aElementTransitions) {
     aElementTransitions =
       GetElementTransitions(aElement, aNewStyleContext->GetPseudoType(),
                             true);
     if (!aElementTransitions) {
       NS_WARNING("allocating ElementTransitions failed");
       return;
     }
   }
   nsTArray<ElementPropertyTransition> &pts =
     aElementTransitions->mPropertyTransitions;
 #ifdef DEBUG
   for (uint32_t i = 0, i_end = pts.Length(); i < i_end; ++i) {
     NS_ABORT_IF_FALSE(pts[i].mProperties.Length() == 1,
                       "Should have one animation property for a transition");
     NS_ABORT_IF_FALSE(i == currentIndex ||
                       pts[i].mProperties[0].mProperty != aProperty,
                       "duplicate transitions for property");
   }
 #endif
   if (haveCurrentTransition) {
     pts[currentIndex] = pt;
   } else {
     if (!pts.AppendElement(pt)) {
       NS_WARNING("out of memory");
       return;
     }
   }
   aElementTransitions->UpdateAnimationGeneration(mPresContext);
   nsRestyleHint hint =
     aNewStyleContext->GetPseudoType() ==
       nsCSSPseudoElements::ePseudo_NotPseudoElement ?
     eRestyle_Self : eRestyle_Subtree;
   presContext->PresShell()->RestyleForAnimation(aElement, hint);
   *aStartedAny = true;
   aWhichStarted->AddProperty(aProperty);
 }
 ElementTransitions*
 nsTransitionManager::GetElementTransitions(dom::Element *aElement,
                                            nsCSSPseudoElements::Type aPseudoType,
                                            bool aCreateIfNeeded)
 {
   if (!aCreateIfNeeded && PR_CLIST_IS_EMPTY(&mElementData)) {
     // Early return for the most common case.
     return nullptr;
   }
   nsIAtom *propName;
   if (aPseudoType == nsCSSPseudoElements::ePseudo_NotPseudoElement) {
     propName = nsGkAtoms::transitionsProperty;
   } else if (aPseudoType == nsCSSPseudoElements::ePseudo_before) {
     propName = nsGkAtoms::transitionsOfBeforeProperty;
   } else if (aPseudoType == nsCSSPseudoElements::ePseudo_after) {
     propName = nsGkAtoms::transitionsOfAfterProperty;
   } else {
     NS_ASSERTION(!aCreateIfNeeded,
                  "should never try to create transitions for pseudo "
                  "other than :before or :after");
     return nullptr;
   }
   ElementTransitions *et = static_cast<ElementTransitions*>(
                              aElement->GetProperty(propName));
   if (!et && aCreateIfNeeded) {
     // FIXME: Consider arena-allocating?
     et = new ElementTransitions(aElement, propName, this,
       mPresContext->RefreshDriver()->MostRecentRefresh());
     nsresult rv = aElement->SetProperty(propName, et,
                                         ElementTransitionsPropertyDtor, false);
     if (NS_FAILED(rv)) {
       NS_WARNING("SetProperty failed");
       delete et;
       return nullptr;
     }
     if (propName == nsGkAtoms::transitionsProperty) {
       aElement->SetMayHaveAnimations();
     }
     AddElementData(et);
   }
   return et;
 }
 /*
  * nsIStyleRuleProcessor implementation
  */
 void
 nsTransitionManager::WalkTransitionRule(ElementDependentRuleProcessorData* aData,
                                         nsCSSPseudoElements::Type aPseudoType)
 {
   ElementTransitions *et =
     GetElementTransitions(aData->mElement, aPseudoType, false);
   if (!et) {
     return;
   }
   if (!mPresContext->IsDynamic()) {
     // For print or print preview, ignore animations.
     return;
   }
   if (aData->mPresContext->IsProcessingRestyles() &&
       !aData->mPresContext->IsProcessingAnimationStyleChange()) {
     // If we're processing a normal style change rather than one from
     // animation, don't add the transition rule.  This allows us to
     // compute the new style value rather than having the transition
     // override it, so that we can start transitioning differently.
     // We need to immediately restyle with animation
     // after doing this.
     nsRestyleHint hint =
       aPseudoType == nsCSSPseudoElements::ePseudo_NotPseudoElement ?
       eRestyle_Self : eRestyle_Subtree;
     mPresContext->PresShell()->RestyleForAnimation(aData->mElement, hint);
     return;
   }
   et->EnsureStyleRuleFor(
     aData->mPresContext->RefreshDriver()->MostRecentRefresh());
   aData->mRuleWalker->Forward(et->mStyleRule);
 }
 /* virtual */ void
 nsTransitionManager::RulesMatching(ElementRuleProcessorData* aData)
 {
   NS_ABORT_IF_FALSE(aData->mPresContext == mPresContext,
                     "pres context mismatch");
   WalkTransitionRule(aData,
                      nsCSSPseudoElements::ePseudo_NotPseudoElement);
 }
 /* virtual */ void
 nsTransitionManager::RulesMatching(PseudoElementRuleProcessorData* aData)
 {
   NS_ABORT_IF_FALSE(aData->mPresContext == mPresContext,
                     "pres context mismatch");
   // Note:  If we're the only thing keeping a pseudo-element frame alive
   // (per ProbePseudoStyleContext), we still want to keep it alive, so
   // this is ok.
   WalkTransitionRule(aData, aData->mPseudoType);
 }
 /* virtual */ void
 nsTransitionManager::RulesMatching(AnonBoxRuleProcessorData* aData)
 {
 }
 #ifdef MOZ_XUL
 /* virtual */ void
 nsTransitionManager::RulesMatching(XULTreeRuleProcessorData* aData)
 {
 }
 #endif
 /* virtual */ size_t
 nsTransitionManager::SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const
 {
   return CommonAnimationManager::SizeOfExcludingThis(aMallocSizeOf);
 }
 /* virtual */ size_t
 nsTransitionManager::SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const
 {
   return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
 }
 struct TransitionEventInfo {
   nsCOMPtr<nsIContent> mElement;
   InternalTransitionEvent mEvent;
   TransitionEventInfo(nsIContent *aElement, nsCSSProperty aProperty,
                       TimeDuration aDuration, const nsAString& aPseudoElement)
     : mElement(aElement)
     , mEvent(true, NS_TRANSITION_END)
   {
     // XXX Looks like nobody initialize WidgetEvent::time
     mEvent.propertyName =
       NS_ConvertUTF8toUTF16(nsCSSProps::GetStringValue(aProperty));
     mEvent.elapsedTime = aDuration.ToSeconds();
     mEvent.pseudoElement = aPseudoElement;
   }
   // InternalTransitionEvent doesn't support copy-construction, so we need
   // to ourselves in order to work with nsTArray
   TransitionEventInfo(const TransitionEventInfo &aOther)
     : mElement(aOther.mElement)
     , mEvent(true, NS_TRANSITION_END)
   {
     mEvent.AssignTransitionEventData(aOther.mEvent, false);
   }
 };
 /* virtual */ void
 nsTransitionManager::WillRefresh(mozilla::TimeStamp aTime)
 {
   NS_ABORT_IF_FALSE(mPresContext,
                     "refresh driver should not notify additional observers "
                     "after pres context has been destroyed");
   if (!mPresContext->GetPresShell()) {
     // Someone might be keeping mPresContext alive past the point
     // where it has been torn down; don't bother doing anything in
     // this case.  But do get rid of all our transitions so we stop
     // triggering refreshes.
     RemoveAllElementData();
     return;
   }
   FlushTransitions(Can_Throttle);
 }
 void
 nsTransitionManager::FlushTransitions(FlushFlags aFlags)
 {
   if (PR_CLIST_IS_EMPTY(&mElementData)) {
     // no transitions, leave early
     return;
   }
   nsTArray<TransitionEventInfo> events;
   TimeStamp now = mPresContext->RefreshDriver()->MostRecentRefresh();
   bool didThrottle = false;
   // Trim transitions that have completed, post restyle events for frames that
   // are still transitioning, and start transitions with delays.
   {
     PRCList *next = PR_LIST_HEAD(&mElementData);
     while (next != &mElementData) {
       ElementTransitions *et = static_cast<ElementTransitions*>(next);
       next = PR_NEXT_LINK(next);
       bool canThrottleTick = aFlags == Can_Throttle &&
         et->CanPerformOnCompositorThread(
           CommonElementAnimationData::CanAnimateFlags(0)) &&
         et->CanThrottleAnimation(now);
       NS_ABORT_IF_FALSE(et->mElement->GetCurrentDoc() ==
                           mPresContext->Document(),
                         "Element::UnbindFromTree should have "
                         "destroyed the element transitions object");
       uint32_t i = et->mPropertyTransitions.Length();
       NS_ABORT_IF_FALSE(i != 0, "empty transitions list?");
       bool transitionStartedOrEnded = false;
       do {
         --i;
         ElementPropertyTransition &pt = et->mPropertyTransitions[i];
         if (pt.IsRemovedSentinel()) {
           // Actually remove transitions one throttle-able cycle after their
           // completion. We only clear on a throttle-able cycle because that
           // means it is a regular restyle tick and thus it is safe to discard
           // the transition. If the flush is not throttle-able, we might still
           // have new transitions left to process. See comment below.
           if (aFlags == Can_Throttle) {
             et->mPropertyTransitions.RemoveElementAt(i);
           }
         } else if (pt.mStartTime + pt.mDelay + pt.mIterationDuration <= now) {
           MOZ_ASSERT(pt.mProperties.Length() == 1,
                      "Should have one animation property for a transition");
           nsCSSProperty prop = pt.mProperties[0].mProperty;
           if (nsCSSProps::PropHasFlags(prop, CSS_PROPERTY_REPORT_OTHER_NAME))
           {
             prop = nsCSSProps::OtherNameFor(prop);
           }
           nsIAtom* ep = et->mElementProperty;
           NS_NAMED_LITERAL_STRING(before, "::before");
           NS_NAMED_LITERAL_STRING(after, "::after");
           events.AppendElement(
             TransitionEventInfo(et->mElement, prop, pt.mIterationDuration,
                                 ep == nsGkAtoms::transitionsProperty ?
                                   EmptyString() :
                                   ep == nsGkAtoms::transitionsOfBeforeProperty ?
                                     before :
                                     after));
           // Leave this transition in the list for one more refresh
           // cycle, since we haven't yet processed its style change, and
           // if we also have (already, or will have from processing
           // transitionend events or other refresh driver notifications)
           // a non-animation style change that would affect it, we need
           // to know not to start a new transition for the transition
           // from the almost-completed value to the final value.
           pt.SetRemovedSentinel();
           et->UpdateAnimationGeneration(mPresContext);
           transitionStartedOrEnded = true;
         } else if (pt.mStartTime + pt.mDelay <= now && canThrottleTick &&
                    !pt.mIsRunningOnCompositor) {
           // Start a transition with a delay where we should start the
           // transition proper.
           et->UpdateAnimationGeneration(mPresContext);
           transitionStartedOrEnded = true;
         }
       } while (i != 0);
       // We need to restyle even if the transition rule no longer
       // applies (in which case we just made it not apply).
       NS_ASSERTION(et->mElementProperty == nsGkAtoms::transitionsProperty ||
                    et->mElementProperty == nsGkAtoms::transitionsOfBeforeProperty ||
                    et->mElementProperty == nsGkAtoms::transitionsOfAfterProperty,
                    "Unexpected element property; might restyle too much");
       if (!canThrottleTick || transitionStartedOrEnded) {
         nsRestyleHint hint = et->mElementProperty == nsGkAtoms::transitionsProperty ?
           eRestyle_Self : eRestyle_Subtree;
         mPresContext->PresShell()->RestyleForAnimation(et->mElement, hint);
       } else {
         didThrottle = true;
       }
       if (et->mPropertyTransitions.IsEmpty()) {
         et->Destroy();
         // |et| is now a dangling pointer!
         et = nullptr;
       }
     }
   }
   if (didThrottle) {
     mPresContext->Document()->SetNeedStyleFlush();
   }
   for (uint32_t i = 0, i_end = events.Length(); i < i_end; ++i) {
     TransitionEventInfo &info = events[i];
     EventDispatcher::Dispatch(info.mElement, mPresContext, &info.mEvent);
     if (!mPresContext) {
       break;
     }
   }
 }

The Tor Browser / annotate

layout/style/nsTransitionManager.cpp@b8a032363ba2 (annotated)

layout/style/nsTransitionManager.cpp